1. Technical Field of the Invention
The present invention relates in general to the telecommunications field, and in particular, to a method and system for implementing a Network Access Server (NAS) in association with a telecommunications switch.
2. Description of Related Art
Access to the Internet is increasingly desirable to achieve economic, educational, and communicative purposes. Individuals typically access the Internet from a personal electronic device such as a computer, personal digital assistant, or cellular phone. Subscribers in a public telephone network establish data connections to the Internet over an NAS. The data connections to an NAS are established over Plain Old Telephone Service (POTS) phone lines or Integrated Services Digital Network (ISDN) lines. At the subscriber end, normal POTS modems or ISDN network terminals (NT-Is, or network terminals on an ISDN connection) are used to initiate the communications. Personal computers with suitable communications software and hardware are frequently used as the terminal in conjunction with either a modem or NT-I.
The NAS acts as a router and concentrator for Internet Protocol (IP) packets that arrive via the data connections. The link level of the incoming data connections can also be terminated at the NAS. For analog lines, such as those originating with a POTS modem, modem pools may be provided at the NAS. IP packets are forwarded to an Internet gateway through various possible channels from the NAS. The IP packets are then transported over the Internet to the appropriate Internet destination.
In summary, an NAS accepts modem or ISDN calls to an Internet service provider (ISP), terminates the phone connection, and interprets the link layer protocol, e.g., Point to Point Protocol (PPP). The IP data packets are then forwarded to the Internet or possibly an intranet.
An NAS typically has an internal network for receiving and routing packets to the Internet. The internal network includes both electronic devices and one or more edge routers (e.g., an Internet Point-of-Presence, or INET-POP). The electronic devices are important for terminating the phone line connection and reformatting a subscriber""s data to comport with the Internet protocol. In a conventional NAS, however, the processing of incoming calls from subscribers is independent of the telecommunication signaling of the associated telecommunications switch.
Typically, the NAS will transmit a B-Answer to the telecommunications network as soon as the incoming call is connected to the NAS. The calling subscriber, however, ultimately desires a connection to the Internet, not the intermediate NAS. Unfortunately, the transmission of the B-Answer begins the billing procedure even before the NAS has begun to establish a link to the Internet. Moreover, the attempt to establish a link (e.g., through PPP) may fail. As a result, the subscriber may be billed for a connection to the Internet that is never provided.
In summary, conventional NASs in conjunction with associated telecommunication switches do not (i) combine telecommunication signaling with the link establishment procedure of the NAS, or (ii) ensure that a subscriber will receive Internet communication service prior to billing the subscriber for using the telecommunications network.
The present invention provides a method and apparatus for an NAS in association with a telecommunications switch whereby computer protocols are combined with telecommunications signaling. Consequently, a subscriber is only billed for telecommunications network use that occurs as a result of, and in direct proportion to, private network communication throughput provided to the subscriber.
Incoming calls to the telecommunications switch that are intended to access a private network such as the Internet are routed to the NAS. In a preferred embodiment, the NAS includes a group of processing devices that provide formatting changes for information being transmitted from the public telephone network to a private network such as the Internet, and vice versa. The processing devices are interconnected via an Ethernet network and include a router that is a gateway to the Internet.
A mutually-understood computer protocol determines the framing and other parameters under which information is transmitted across a communication link from a subscriber""s point to the point of the NAS. In a preferred embodiment, a PPP governs these link options. The PPP includes five phases, which are the dead, establish, authenticate, network, and terminate phases. Information throughput from the subscriber to the Internet is possible in the network phase.
According to a first aspect of the present invention, a B-Answer communication is sent from the NAS to the telecommunications switch (and then onward to the telecommunications network as a B-Answer signal) after the network phase is entered. In a specific implementation of this first aspect, a negotiation of network parameters, IP addresses, etc. occurs during the network phase. Once this negotiation is complete, an open state (e.g., in a PPP) is attained and the B-Answer communication may be issued. According to a second aspect of the present invention, a B-on-Hook signal is sent from the NAS to the telecommunications switch (and then onward to the telecommunications network as a B-on-Hook signal) after the network phase begins to conclude but before the communication link is completely terminated. The calling subscriber is therefore only billed while information throughput to the Internet is possible.
An important technical advantage of the present invention is that subscribers will not be billed for service that they do not receive.
Another important technical advantage of the present invention is that subscribers will not be billed for telecommunications network use unless/until an Internet connection can be set-up (and preferably authenticated) for a calling subscriber.
Yet another important technical advantage of the present invention is that an NAS can delay the transmission of a B-Answer signal until a network-layer phase of the PPP is set-up.
Yet another important technical advantage of the present invention is that an NAS can transmit a B-on-Hook signal before entering a dead phase of the PPP.
The above-described and other features of the present invention are explained in detail hereinafter with reference to the illustrative examples shown in the accompanying drawings. Those skilled in the art will appreciate that the described embodiments are provided for purposes of illustration and understanding and that numerous equivalent embodiments are contemplated herein.